Speaker：Yimo Han, assistant professor of Materials Science and NanoEngineering, Rice University
Inviter：Yujun Xie
Time：10:00, December 27, 2023 (Beijing Time)
Location：200, Yue-Kong Pao Library's Annex
Abstract：
Two-dimensional (2D) materials and their heterostructures have emerged as key components for innovative applications and exhibit unique properties distinct from bulk materials. Understanding the behavior of strain and deformation in 2D materials is crucial for their potential device applications and offers valuable insights into precisely engineering nano-scale strain in these layered materials. In this study, utilizing nanobeam four-dimensional scanning transmission electron microscopy (4D-STEM), we introduce novel approaches to investigate both in-plane and out-of-plane strain and deformation in 2D materials. Our findings reveal a new mechanism of strain relaxation in 2D materials through the formation of out-of-plane ripples. Additionally, we uncover how 2D materials employ long-range lattice rotation and confined nanoscale uniaxial strain to compensate for lattice mismatch, and we elucidate different stacking orders in van der Waals heterostructures mediated by interlayer strain effects.
[1] Chuqiao Shi, … Yimo Han “Domain-dependent Strain and Stacking in Two-dimensional van der Waals Ferroelectrics,” Nature Communications, 14, 7168 (2023).
[2] Y. Han, et al. “Sub-nanometer Channels Embedded in Two-Dimensional Materials,” Nature Materials, 17, 129-133 (2018).
[3] Y. Han, et al. “Strain Mapping of Two-dimensional Heterostructures with Sub-picometer Precision,” Nano Letters, 18, 3746-3751 (2018).
[4] S. Xie, L. Tu*, Y. Han*, et al. “Coherent Atomically-thin Superlattices with Engineered Strain,” Science, 359, 1131-1136 (2018).
Biography：
Dr. Han is an assistant professor of Materials Science and NanoEngineering at Rice University. She earned her B.S. in Physics from Tsinghua University and her Ph.D. in Applied Physics from Cornell University. Following this, she completed postdoctoral training in the Department of Molecular Biology at Princeton University. Her research is dedicated to advancing electron microscopy methods to explore low-dimensional nanomaterials. She is the recipient of the NSF CAREER award, Roy E. Campbell Faculty Development Award, and was listed on the 2022 MIT TR 35 China list.
